A system consisting of communication devices, such as servers or storage devices, which are connected to each other with communication cables is generally known. In a case where each of the communication devices has a plurality of connectors, each having the same shape, there is a possibility that one connector of one communication device is mistakenly connected with an improper connector of another communication device.
It is possible to avoid such misconnection by making the shape of connectors different from each other. However, such a solution requires a plurality of types of communication cables which have different connector shapes, and thereby increases both cost and complexity.